Illumination device and projection type display device using the same

Abstract

Illumination device includes a light source (101); an illumination optical system (102, 103, 104, 106, 107) that spatially splits each of the plurality of color light beams emitted from the light source, superimposes the split light beams of each of the plurality of color light beams, and emits the superimposed light beams to a display element (110); a reflective polarization plate (109) that is arranged between the illumination optical system (102, 103, 104, 106, 107) and the display element (110) and that transmits first polarized light and reflects second polarized light whose polarization state is different from that of the first polarized light toward the illumination optical system (102, 103, 104, 106, 107); a reflection element (105) that is arranged at a position where each of the plurality of color light beams is spatially split by the illumination optical system and that transmits the split light beams of each of the color light beams and reflects, of the split light beams of each of the color light beams that have been transmitted through the reflective polarization plate (109), each color light beam reflected by the reflective polarization plate toward the reflective polarization plate (109); and a phase plate (108) arranged between the reflection element (105) and the reflective polarization plate (109).

Description

TECHNICAL FIELD[0001]The present invention relates to an illumination device for a projection type display device represented by a liquid crystal projector, in particular, to an illumination device that illuminates a display element including a reflective polarization conversion element.BACKGROUND ART[0002]Patent Literatures 1 and 2 discuss a projector that uses a LED (Light Emitting Diode) as a light source for illuminating a DMD (Digital Micromirror Device) serving as a display element. The projector of this type is expected to reduce costs more than a projector that uses a discharge lamp, and achieve performance including miniaturization, lower power consumption, and a wider color reproduction range.[0003]There are also a projector that uses a single LCoS (Liquid Crystal on Silicon) element (Nonpatent Literature 1), and a projector that users three liquid crystal panels as display elements (Nonpatent Literatures 2 and 3).[0004]In the liquid crystal projector, usually, a liquid cr...

AI Technical Summary

Benefits of technology

[0021]The light of the polarized component reflected by the reflective polarization plate efficiently returns to the surface of the LED. However, on the surface of the LED, only a part of the returned light is reflected toward the polarization plate. Thus, a light loss occurs on the surface of the LED, thus preventing realization of high polarizing conversion efficiency.

[0024]An object of the present invention is to provide a small illumination device and projection type display device that uses the illumination device that can solve the foregoing problems and improve polarization conversion efficiency and thereby light use efficiency.

Problems solved by technology

Thus, a light loss occurs on the surface of the LED, thus preventing realization of high polarizing conversion efficiency.

Since the illumination device presented in Patent Literature 3 uses a PBS polarization conversion array, it is difficult to miniaturize the illumination device.

If the first and second prisms are formed in such a pitch, it will be difficult to adhere the half-wave plate on the second prism.

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